Method and apparatus for reporting feedback information for multi-carrier operation

ABSTRACT

Method and apparatus for reporting feedback information for multi-carrier operation are disclosed. A wireless transmit/receive unit (WTRU) is configured with multiple carriers. A base station may allocate an uplink (UL) control channel associated with a single UL carrier, for the WTRU. The base station may transmit, to the WTRU, a plurality of data signals via at least two downlink (DL) carriers using orthogonal frequency division multiple access (OFDMA) and multiple input multiple output (MIMO), and may receive from the WTRU hybrid automatic repeat request (HARQ) acknowledgment/negative-acknowledgement (ACK/NACK) information, for the plurality of data signals transmitted via the at least two DL carriers, on the UL control channel. The HARQ ACK/NACK information may include at least two HARQ ACK/NACKs ANDed together. In addition, the base station may transmit, to the WTRU, information including a set of the DL carriers, each having an associated three bit indicator, for DL data transmission.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/868,214 filed Aug. 25, 2010, which claims the benefit of U.S.Provisional Application No. 61/236,912 filed Aug. 26, 2009, the contentsof which are hereby incorporated by reference herein.

BACKGROUND

Multi-carrier operation improves achievable throughput and coverage ofwireless access systems. In multi-carrier operation, a wirelesstransmit/receive unit (WTRU) may be configured and activate more thanone frequency carrier in the uplink (UL) and/or in the downlink (DL).The multi-carrier operations would allow UL and DL transmissionbandwidths to exceed a single carrier frequency and allow for moreflexible and more efficient usage of the available spectrums.

For flexible and efficient usage of the available spectrums and foreffective support for the asymmetric traffic loads in the DL, themulti-carrier configuration with an unpaired DL carrier(s) has beenproposed. An unpaired DL carrier is a DL carrier that does not have acorresponding UL carrier. For example, in frequency division duplex(FDD) systems, the DL may contain a first 20 MHz carrier and a second 10MHz carrier and the UL may have a 20 MHz carrier. In this example, thesecond DL 10 MHz carrier, which does not have a paired UL carrier, is anunpaired DL carrier. The unpaired DL carrier may occur in time divisionduplex (TDD) systems as well. For example, a subscriber may have a firstcarrier activated on both the DL and the UL and a second carrieractivated only on the DL, where the second carrier with only DLactivation is an unpaired DL carrier. Another example of unpaired DLcarrier is a partially configured carrier, which is defined as DL-onlytransmission carrier in TDD or a DL carrier without paired UL carrier inFDD.

SUMMARY

Method and apparatus for reporting feedback information formulti-carrier operation are disclosed. For effective support for theasymmetric traffic loads in the downlink, a WTRU may be configured withmultiple carriers with an unpaired downlink carrier(s). The unpaireddownlink carrier is an active downlink carrier that does not have acorresponding active uplink carrier. The WTRU reports feedbackinformation for multi-carrier operation including feedback for theunpaired downlink carrier. For transmission of the feedback informationfor the unpaired downlink carrier, a feedback channel may be allocatedon a distinct non-overlapping resource region on the uplink carrier sothat the network may determine which downlink carrier the receivedfeedback information is for based on the resource region. Alternatively,a different feedback channel may be allocated for the unpaired downlinkcarrier.

The feedback information for the unpaired downlink carrier may betransmitted based on a pre-determined pattern on a feedback channel. Thefeedback information for the unpaired downlink carrier may betransmitted via a physical control channel. Alternatively, the feedbackinformation may be transmitted via medium access control (MAC) encodedfeedback such as MAC signaling header, MAC subheader, MAC extendedheader, MAC extended subheader, and/or MAC management message.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example in conjunction with the accompanying drawingswherein:

FIG. 1A is a system diagram of an example communications system in whichone or more disclosed embodiments may be implemented;

FIG. 1B is a system diagram of an example wireless transmit/receive unit(WTRU) that may be used within the communications system illustrated inFIG. 1A;

FIG. 1C is a system diagram of an example radio access network and anexample core network that may be used within the communications systemillustrated in FIG. 1A;

FIG. 2 is a flow diagram of an example process for reporting feedbackinformation for multi-carrier operation;

FIG. 3 shows a conventional data randomizer;

FIG. 4 shows a coding chain 400 at a transmitting side;

FIG. 5 shows an example scheme for indicating the DL carrier usingfeedback channel allocation;

FIG. 6 shows an example scheme for indicating the DL carrier usingfeedback channel usage pattern; and

FIG. 7 shows an example scheme for supporting feedback for unpaired DLcarrier with feedback region level allocation.

DETAILED DESCRIPTION

FIG. 1A is a diagram of an example communications system 100 in whichone or more disclosed embodiments may be implemented. The communicationssystem 100 may be a multiple access system that provides content, suchas voice, data, video, messaging, broadcast, etc., to multiple wirelessusers. The communications system 100 may enable multiple wireless usersto access such content through the sharing of system resources,including wireless bandwidth. For example, the communications systems100 may employ one or more channel access methods, such as code divisionmultiple access (CDMA), time division multiple access (TDMA), frequencydivision multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrierFDMA (SC-FDMA), and the like.

As shown in FIG. 1A, the communications system 100 may include wirelesstransmit/receive units (WTRUs) 102 a, 102 b, 102 c, 102 d, a radioaccess network (RAN) 104, a core network 106, a public switchedtelephone network (PSTN) 108, the Internet 110, and other networks 112,though it will be appreciated that the disclosed embodiments contemplateany number of WTRUs, base stations, networks, and/or network elements.Each of the WTRUs 102 a, 102 b, 102 c, 102 d may be any type of deviceconfigured to operate and/or communicate in a wireless environment. Byway of example, the WTRUs 102 a, 102 b, 102 c, 102 d may be configuredto transmit and/or receive wireless signals and may include userequipment (UE), a mobile station, a fixed or mobile subscriber unit, apager, a cellular telephone, a personal digital assistant (PDA), asmartphone, a laptop, a netbook, a personal computer, a wireless sensor,consumer electronics, and the like.

The communications systems 100 may also include a base station 114 a anda base station 114 b. Each of the base stations 114 a, 114 b may be anytype of device configured to wirelessly interface with at least one ofthe WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to one or morecommunication networks, such as the core network 106, the Internet 110,and/or the networks 112. By way of example, the base stations 114 a, 114b may be a base transceiver station (BTS), a Node-B, an eNode B, a HomeNode B, a Home eNode B, a site controller, an access point (AP), awireless router, and the like. While the base stations 114 a, 114 b areeach depicted as a single element, it will be appreciated that the basestations 114 a, 114 b may include any number of interconnected basestations and/or network elements.

The base station 114 a may be part of the RAN 104, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, etc. The base station 114 a and/or the base station 114 b may beconfigured to transmit and/or receive wireless signals within aparticular geographic region, which may be referred to as a cell (notshown). The cell may further be divided into cell sectors. For example,the cell associated with the base station 114 a may be divided intothree sectors. Thus, in one embodiment, the base station 114 a mayinclude three transceivers, i.e., one for each sector of the cell. Inanother embodiment, the base station 114 a may employ multiple-inputmultiple output (MIMO) technology and, therefore, may utilize multipletransceivers for each sector of the cell.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 116, which may beany suitable wireless communication link (e.g., radio frequency (RF),microwave, infrared (IR), ultraviolet (UV), visible light, etc.). Theair interface 116 may be established using any suitable radio accesstechnology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 104 and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Universal MobileTelecommunications System (UMTS) Terrestrial Radio Access (UTRA), whichmay establish the air interface 116 using wideband CDMA (WCDMA). WCDMAmay include communication protocols such as High-Speed Packet Access(HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed DownlinkPacket Access (HSDPA) and/or High-Speed Uplink Packet Access (HSUPA).

In another embodiment, the base station 114 a and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Evolved UMTSTerrestrial Radio Access (E-UTRA), which may establish the air interface116 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.16 (i.e.,Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000,CDMA2000 1×, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), InterimStandard 95 (IS-95), Interim Standard 856 (IS-856), Global System forMobile communications (GSM), Enhanced Data rates for GSM Evolution(EDGE), GSM EDGE (GERAN), and the like.

The base station 114 b in FIG. 1A may be a wireless router, Home Node B,Home eNode B, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, and the like. In oneembodiment, the base station 114 b and the WTRUs 102 c, 102 d mayimplement a radio technology such as IEEE 802.11 to establish a wirelesslocal area network (WLAN). In another embodiment, the base station 114 band the WTRUs 102 c, 102 d may implement a radio technology such as IEEE802.15 to establish a wireless personal area network (WPAN). In yetanother embodiment, the base station 114 b and the WTRUs 102 c, 102 dmay utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, etc.) to establish a picocell or femtocell. As shown in FIG. 1A,the base station 114 b may have a direct connection to the Internet 110.Thus, the base station 114 b may not be required to access the Internet110 via the core network 106.

The RAN 104 may be in communication with the core network 106, which maybe any type of network configured to provide voice, data, applications,and/or voice over internet protocol (VoIP) services to one or more ofthe WTRUs 102 a, 102 b, 102 c, 102 d. For example, the core network 106may provide call control, billing services, mobile location-basedservices, pre-paid calling, Internet connectivity, video distribution,etc., and/or perform high-level security functions, such as userauthentication. Although not shown in FIG. 1A, it will be appreciatedthat the RAN 104 and/or the core network 106 may be in direct orindirect communication with other RANs that employ the same RAT as theRAN 104 or a different RAT. For example, in addition to being connectedto the RAN 104, which may be utilizing an E-UTRA radio technology, thecore network 106 may also be in communication with another RAN (notshown) employing a GSM radio technology.

The core network 106 may also serve as a gateway for the WTRUs 102 a,102 b, 102 c, 102 d to access the PSTN 108, the Internet 110, and/orother networks 112. The PSTN 108 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet110 may include a global system of interconnected computer networks anddevices that use common communication protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) andthe internet protocol (IP) in the TCP/IP internet protocol suite. Thenetworks 112 may include wired or wireless communications networks ownedand/or operated by other service providers. For example, the networks112 may include another core network connected to one or more RANs,which may employ the same RAT as the RAN 104 or a different RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities, i.e., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks. For example, the WTRU 102 c shown in FIG. 1A may be configured tocommunicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology.

FIG. 1B is a system diagram of an example WTRU 102. As shown in FIG. 1B,the WTRU 102 may include a processor 118, a transceiver 120, atransmit/receive element 122, a speaker/microphone 124, a keypad 126, adisplay/touchpad 128, non-removable memory 106, removable memory 132, apower source 134, a global positioning system (GPS) chipset 136, andother peripherals 138. It will be appreciated that the WTRU 102 mayinclude any sub-combination of the foregoing elements while remainingconsistent with an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Array (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit/receive element 122. While FIG. 1Bdepicts the processor 118 and the transceiver 120 as separatecomponents, it will be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, thetransmit/receive element 122 may be an antenna configured to transmitand/or receive RF signals. In another embodiment, the transmit/receiveelement 122 may be an emitter/detector configured to transmit and/orreceive IR, UV, or visible light signals, for example. In yet anotherembodiment, the transmit/receive element 122 may be configured totransmit and receive both RF and light signals. It will be appreciatedthat the transmit/receive element 122 may be configured to transmitand/or receive any combination of wireless signals.

In addition, although the transmit/receive element 122 is depicted inFIG. 1B as a single element, the WTRU 102 may include any number oftransmit/receive elements 122. More specifically, the WTRU 102 mayemploy MIMO technology. Thus, in one embodiment, the WTRU 102 mayinclude two or more transmit/receive elements 122 (e.g., multipleantennas) for transmitting and receiving wireless signals over the airinterface 116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as UTRA and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 106 and/or the removable memory 132.The non-removable memory 106 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station (e.g., base stations 114 a, 114 b) and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. It will be appreciated that the WTRU 102 mayacquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, and the like.

The processor 118 is configured to perform, either alone or incombination with software, the methods in accordance with one or anycombination of the embodiments disclosed herein.

FIG. 1C is a system diagram of the RAN 104 and the core network 106according to an embodiment. The RAN 104 may be an access service network(ASN) that employs IEEE 802.16 radio technology to communicate with theWTRUs 102 a, 102 b, 102 c over the air interface 116. As will be furtherdiscussed below, the communication links between the differentfunctional entities of the WTRUs 102 a, 102 b, 102 c, the RAN 104, andthe core network 106 may be defined as reference points.

As shown in FIG. 1C, the RAN 104 may include base stations 140 a, 140 b,140 c, and an ASN gateway 142, though it will be appreciated that theRAN 104 may include any number of base stations and ASN gateways whileremaining consistent with an embodiment. The base stations 140 a, 140 b,140 c may each be associated with a particular cell (not shown) in theRAN 104 and may each include one or more transceivers for communicatingwith the WTRUs 102 a, 102 b, 102 c over the air interface 116. In oneembodiment, the base stations 140 a, 140 b, 140 c may implement MIMOtechnology. Thus, the base station 140 a, for example, may use multipleantennas to transmit wireless signals to, and receive wireless signalsfrom, the WTRU 102 a. The base stations 140 a, 140 b, 140 c may alsoprovide mobility management functions, such as handoff triggering,tunnel establishment, radio resource management, traffic classification,quality of service (QoS) policy enforcement, and the like. The ASNgateway 142 may serve as a traffic aggregation point and may beresponsible for paging, caching of subscriber profiles, routing to thecore network 106, and the like.

The air interface 116 between the WTRUs 102 a, 102 b, 102 c and the RAN104 may be defined as an R1 reference point that implements the IEEE802.16 specification. In addition, each of the WTRUs 102 a, 102 b, 102 cmay establish a logical interface (not shown) with the core network 106.The logical interface between the WTRUs 102 a, 102 b, 102 c and the corenetwork 106 may be defined as an R2 reference point, which may be usedfor authentication, authorization, IP host configuration management,and/or mobility management.

The communication link between each of the base stations 140 a, 140 b,140 c may be defined as an R8 reference point that includes protocolsfor facilitating WTRU handovers and the transfer of data between basestations. The communication link between the base stations 140 a, 140 b,140 c and the ASN gateway 215 may be defined as an R6 reference point.The R6 reference point may include protocols for facilitating mobilitymanagement based on mobility events associated with each of the WTRUs102 a, 102 b, 100 c.

As shown in FIG. 1C, the RAN 104 may be connected to the core network106. The communication link between the RAN 104 and the core network 106may defined as an R3 reference point that includes protocols forfacilitating data transfer and mobility management capabilities, forexample. The core network 106 may include a mobile IP home agent(MIP-HA) 144, an authentication, authorization, accounting (AAA) server146, and a gateway 148. While each of the foregoing elements aredepicted as part of the core network 106, it will be appreciated thatany one of these elements may be owned and/or operated by an entityother than the core network operator.

The MIP-HA may be responsible for IP address management, and may enablethe WTRUs 102 a, 102 b, 102 c to roam between different ASNs and/ordifferent core networks. The MIP-HA 144 may provide the WTRUs 102 a, 102b, 102 c with access to packet-switched networks, such as the Internet110, to facilitate communications between the WTRUs 102 a, 102 b, 102 cand IP-enabled devices. The AAA server 146 may be responsible for userauthentication and for supporting user services. The gateway 148 mayfacilitate interworking with other networks. For example, the gateway148 may provide the WTRUs 102 a, 102 b, 102 c with access tocircuit-switched networks, such as the PSTN 108, to facilitatecommunications between the WTRUs 102 a, 102 b, 102 c and traditionalland-line communications devices. In addition, the gateway 148 mayprovide the WTRUs 102 a, 102 b, 102 c with access to the networks 112,which may include other wired or wireless networks that are owned and/oroperated by other service providers.

Although not shown in FIG. 1C, it will be appreciated that the RAN 104may be connected to other ASNs and the core network 106 may be connectedto other core networks. The communication link between the RAN 104 theother ASNs may be defined as an R4 reference point, which may includeprotocols for coordinating the mobility of the WTRUs 102 a, 102 b, 102 cbetween the RAN 104 and the other ASNs. The communication link betweenthe core network 106 and the other core networks may be defined as an R5reference, which may include protocols for facilitating interworkingbetween home core networks and visited core networks.

FIG. 2 is a flow diagram of an example process for reporting feedbackinformation for multi-carrier operation. A WTRU is configured, andactivated, a plurality of DL carriers and at least one uplink carriereither in FDD, TDD, or half duplex FDD mode. The WTRU receives downlinktransmissions via at least two DL carriers including an unpaired DLcarrier (202). The unpaired DL carrier is an active DL carrier that doesnot have a corresponding active UL carrier.

The WTRU then sends feedback information for the unpaired DL carrierwith or without feedback information for the paired DL carrier on anactivated UL carrier (204). For the multi-carrier DL operation, the WTRUneeds to transmit feedback information in the UL to the base station (orany other network entity) for both a paired DL carrier and an unpairedDL carrier. The feedback information may include DL physical layer (PHY)measurement such as carrier-to-interference and noise ratio (CINR), MIMOoperation related feedback information, hybrid automatic repeat request(HARQ) positive acknowledgement/negative acknowledgement (ACK/NACK)feedback, the subscriber's suggestion about the DL operation, (e.g.,subscriber preferred DL modulation and coding schemes, etc.), or anyother information.

The DL carrier with which the feedback information is associated may beimplicitly or explicitly indicated, which will be explained in detailbelow. The activated UL carrier may be a primary UL carrier or asecondary UL carrier.

The feedback information may be sent via a physical control channel,(e.g., fast feedback channel, channel quality indication channel(CQICH), HARQ ACK/NAK channel, and the like as specified in IEEE802.16m), or via medium access control (MAC) encoded feedbacks, (e.g.,MAC signaling header, extended header, subheader, extended subheader,and MAC management messages, and the like), or any other messagingmechanism that may be implemented at different protocol layers.

Embodiments for sending feedback information for the unpaired DL carrierand identifying the DL carrier for the transmitted feedback informationare explained hereafter. It should be noted that even though theembodiments will be explained with reference to an IEEE 802.16m systemusing the terminologies and types of channels and messages specific toIEEE 802.16m, the embodiments are also applicable to any type ofwireless communication systems including, but not limited to, the thirdgeneration partnership project (3GPP) LTE or LTE-Advanced.

In accordance with one embodiment, the feedback information for theunpaired DL carrier(s) (with or without feedback information for thepaired DL carrier(s)) may be reported via a physical control channel onan activated UL carrier. For example, the physical control channel in802.16m may be a fast feedback channel (i.e., a channel qualityindication channel (CQICH)), a HARQ channel, or the like. The activatedUL carrier through which the feedback information is transmitted may bea primary UL carrier or an activated secondary UL carrier. The feedbackinformation may be information about any DL carriers, includingactivated paired or unpaired DL carriers.

The DL carrier to which the transmitted feedback information is relatedmay be identified by a DL carrier identifier (or any equivalent thereof)which is implicitly or explicitly coded in the feedback information.Alternatively, the DL carrier may be identified implicitly by thefeedback allocation. The feedback allocation may be either at thefeedback channel level or at the feedback region level, which will beexplained in detail below.

Example embodiments for sending feedback information for the unpaired DLcarrier(s) via a physical control channel are explained with referenceto 802.16m. In IEEE 802.16m, a primary fast feedback control channel(PFBCH), a secondary fast feedback control channel (SFBCH), or a HARQfeedback control channel (HFBCH) may be used for reporting feedbackinformation.

Each PFBCH carries 6 bits of information providing wideband channelquality feedback, MIMO feedback and the like. The physical resource forthe PFBCH is allocated to the WTRU by a feedback allocation advanced map(A-MAP) information element (IE) in the DL. The PFBCH starts at apre-determined location, (i.e., feedback region), with the size (bothsubcarrier and OFDM symbol) defined in a DL broadcast control message.

Each SFBCH carries 7 to 24 bits of information providing narrowbandchannel quality feedback, MIMO feedback, and the like. The physicalresource for the SFBCH is allocated to the WTRU by a feedback allocationA-MAP IE. The SFBCH starts at a pre-determined location, (i.e., feedbackregion), with the size defined in a DL broadcast control message. Afeedback region is an UL resource allocation on an activated UL carrierthat comprises a plurality of resource units, where a resource unit isthe smallest resource allocation granularity. In IEEE 802.16m, aresource unit comprises 18 subcarriers over 6 OFDM symbols.

Each HFBCH carries 1 bit of information providing an ACK or a NACK for aDL HARQ packet. The HFBCH is allocated to the WTRU through the HARQfeedback allocation (HFA) field in the same DL A-MAP IE that specifiesthe DL allocation for the DL HARQ packet. Such DL A-MAP IEs include DLbasic assignment A-MAP IE, DL individual persistent A-MAP IE, DLcomposite persistent A-MAP IE, and DL group resource allocation A-MAPIE.

The DL carrier identity may be explicitly included in the coded feedbackinformation in the PFBCH or SFBCH. Alternatively, in order to reduce thenumber of bits for specifically indicating the DL carrier identity, acompression scheme may be implemented. For example, the base station maysignal a list of its component carriers and the WTRU may use thecomponent carrier index into the list as a substitute for the DL carrieridentifier. If the number of carriers for any cells is not very large,2-3 bits may be sufficient.

Alternatively, the DL carrier identity may be indicated implicitly bymodifying the physical layer signals in a way that allows the basestation to determine to which DL carrier the feedback information isrelated.

In accordance with one embodiment, a pilot sequence may be modified toindicate the DL carrier identity with which the feedback information isassociated. In IEEE 802.16m, the SFBCH comprises three (3) distributedfeedback mini-tiles (FMTs) and each FMT includes two pilot symbols(i.e., six pilot symbols per SFBCH). The pilot sequence in the SFBCH maybe [1 1 1 1 1 1]. In accordance with one embodiment, the pilot sequencemay be modified to create other pilot sequences which correspond toother DL carrier identifiers (i.e., a different pilot sequence may beused for feedback information for a different DL carrier). The pilotsequences may or may not be orthogonal to each other. The base stationcompares the received pilot sequence in the SFBCH to all possiblesequences to determine which DL carrier identifier corresponds to thetransmitted feedback information on the SFBCH. Alternatively, thereceiver may attempt to decode the data using each possible pilotsequence to check data validity (using a CRC). The carrier identifiermay be used as a CRC mask on the data. In this case, each possible maskis used at the receiver until the CRC passes to determine which carrieridentifier was used at the transmitter to mask the CRC.

In IEEE 802.16m, data randomization is performed on each burst of datausing a data randomizer shown in FIG. 3. As shown in FIG. 3 the inputbit stream is mixed with a bit sequence generated by the randomizer. Thedata randomization is performed for preventing long sequences of ones orzeros. The randomizer is initialized with a predetermined sequence. Inaccordance with another embodiment, the randomizer initializationsequence may be selected depending on the downlink carrier to which thefeedback information is related to so as to indicate which DL carrieridentifier the current feedback information is related to, (i.e., therandomizer may be initialized with a different sequence for feedbackinformation for a different DL carrier).

FIG. 4 shows a coding chain 400 at a transmitting side. When arandomizer 402 is loaded with a sequence based on the DL carrieridentifier, the randomizer 402 produces a randomized stream that isunique to the data and the pre-loaded sequence. A CRC is added to theoutput of the randomizer 402 by the FEC block CRC addition block 403.The data input to the randomizer 402 also has a (burst) CRC added by theburst CRC addition block 401. At the receiver, the FEC block may beverified by CRC check, and then different randomizer preload sequencesmay be tried until the burst CRC check passes, which will provide the DLcarrier identifier.

To determine which DL carrier identifier is being referenced, the basestation may try each of the predetermined preloaded sequences for therandomizer.

In accordance with another embodiment, the DL carrier may be implicitlyindicated based on the feedback allocation. Two levels of feedbackallocations are available for this purpose: feedback channel level andfeedback region level.

One or more feedback channels may be formed in a resource unit dependingon the feedback channel structure. Multiple feedback channels may beallocated to one feedback region. In IEEE 802.16m, the UL fast feedbackchannels, including both PFBCH and SFBCH, are allocated or de-allocatedto the WTRUs by the feedback allocation A-MAP IE. Table 1 shows thebasic structure of the 802.16m feedback allocation A-MAP IE.

TABLE 1 Syntax Size (bit) Notes Feedback-Allocation-A- MAP_IE( ) { A-MAPIE Type 4 Type for the feedback allocation A-MAP IE Channel IndexVariable Feedback channel index within the UL fast feedback controlresource region, dependent on the size of feedback control resourceregion. Short-term feedback 3 A feedback is transmitted on the FBCHevery 2^(p) frames period (p) Long-term feedback 2 A long-term feedbackis transmitted on the FBCH every 2^(q) short- Period (q) term feedbackopportunities. If q = 0b00, long-term feedback is not used Frame offset3 The WTRU starts reporting at the frame of which the number has thesame 3 LSB as the specified frame offset. If the current frame isspecified, the WTRU may start reporting in eight frames. ................ . . Other fields, specifying the feedback channel, e.g., feedbackformat, <Other fields > MIMO mode, . . . MCRC 16  16 bit CRC masked byStation ID }

A “DL carrier identifier” field may be added to the feedback allocationA-MAP IE to indicate the DL carrier for which the feedback channel isallocated so that a separate feedback channel may be allocated for eachDL carrier. Alternatively, the DL carrier identifier may be used as apart of the mask for the CRC. In 802.16m, the CRC field is masked with astation ID (STID). The STID is 12 bits long and the CRC field is 16 bitslong. Therefore, the remaining 4 bits of CRC may be masked with amasking code that contains the DL carrier identity information toindicate which DL carrier the feedback channel allocation is for.

Multiple feedback channels may be allocated to a WTRU, and the WTRU maysend the feedback information for a specific DL carrier in thecorresponding feedback channel so that the base station recognizes whichDL carrier the received feedback information is for based on thefeedback channel on which the feedback information is received. Thefeedback channels may be allocated to a WTRU either by using thefeedback allocation A-MAP IE multiple times or by using a modifiedversion of the feedback allocation A-MAP IE to allocate multiplefeedback channels to the same WTRU.

FIG. 5 shows an example scheme for indicating the DL carrier usingfeedback channel allocation. In FIG. 5, a WTRU has three activatedcarriers, Carrier-1, Carrier-2, and Carrier-3. Carrier-1 is activated inboth DL and UL, Carrier-2 is activated only in DL, and Carrier-3 is aDL-only carrier. Carrier-2 and Carrier-3 are unpaired DL carriers. InFIG. 5, multiple feedback channels are allocated to the WTRU in thefeedback region of the UL carrier, and the WTRU sends the feedback forCarrier-1, Carrier-2 and Carrier-3 on the corresponding allocatedfeedback channel, respectively.

Alternatively, the DL carrier information may be implicitly indicatedthrough mapping the feedback channels to the DL carriers, instead ofexplicitly using a field of DL carrier identifier in the feedbackallocation IE. Multiple feedback channels may be allocated to a WTRUeither by using the conventional feedback allocation A-MAP IE multipletimes or by using a modified version of the feedback allocation A-MAP IEto allocate multiple feedback channels to the same WTRU. The allocatedfeedback channels may have a one-to-one correspondence with the DLcarriers. This correspondence may be either specified by MAC signalingduring the multiple carrier operation initialization for the WTRU or bya pre-defined mapping scheme. For example, the lowest channel index ofthe feedback channel may be assigned for the feedback of the default DLcarrier, and the remaining feedback channels may be mapped to theunpaired DL carriers in the same order of feedback channel index as thecarrier index.

Alternatively, one feedback channel may be assigned to a WTRU andmultiple DL carriers may share the single feedback channel in timedomain, and a pre-agreed feedback channel usage pattern may be definedbetween the base station and the WTRU. The feedback usage patternimplicitly indicates the DL carrier information for feedback sent on thefeedback channel at a specific time. FIG. 6 shows an example scheme forindicating the DL carrier using feedback channel usage pattern. In FIG.6, a WTRU has two activated carriers, Carrier-1 and Carrier-2. Carrier-1is activated in both DL and UL, and Carrier-2 is activated only in DL.Carrier-2 is an unpaired DL carrier. In FIG. 6, a feedback channel isallocated to the WTRU periodically in every two frames. The WTRU and thebase station have a pre-agreed feedback channel usage pattern forsending feedback for multiple DL carriers. For example, the WTRU maysend the feedback for the DL carriers in a round robin fashion, (i.e.,Carrier-1, Carrier-2, Carrier-1, Carrier-2, Carrier-1, . . . ). Thefeedback channel usage pattern may be pre-determined or specified in astandard specification or negotiated between the base station and theWTRU, (e.g., during the multicarrier operation initialization process).

Alternatively, a separate feedback region may be allocated for adifferent DL carrier, and all the feedback channels for the DL carriermay be allocated to the WTRUs in the corresponding feedback region. InIEEE 802.16m, a feedback region is allocated in a pre-determinedlocation with the size specified in DL control signals, (e.g., theSuperFrame Header (SFH)). The base station may allocate a separatefeedback region, (i.e., a distinct non-overlapping region), for each DLcarrier, including paired and unpaired DL carriers. The location andsize of the feedback control region for an unpaired DL carrier may bespecified in DL control signals, (e.g., SuperFrame Header, or in MACmanagement messages). Separate feedback regions may be allocated in timedomain and/or frequency domain.

FIG. 7 shows an example scheme for supporting feedback for unpaired DLcarrier with feedback region level allocation. In FIG. 7, a WTRU hasthree activated carriers, Carrier-1, Carrier-2, and Carrier-3. Carrier-1is activated in both DL and UL, Carrier-2 is activated only in DL, andCarrier-3 is DL-only carrier. Carrier-2 and Carrier-3 are unpaired DLcarriers. In FIG. 7, three separate feedback regions are allocated tothe WTRU for Carrier-1, Carrier-2, and Carrier-3, the WTRU sends thefeedback of the DL carriers on the allocated feedback channel on thecorresponding allocated feedback region.

The embodiments disclosed above may be used for sending HARQ ACK/NACKfeedback, as well. HARQ ACK/NACK feedback is different from the DLchannel feedback in the following aspects. HARQ ACK/NACK is per HARQpacket while DL channel feedback is per WTRU per DL channel. HARQACK/NACK usually carries 1-bit information while DL channel feedbackrequires more information bits. HARQ ACK/NACK allocation to a HARQpacket is usually specified in conjunction with the HARQ packetallocation implicitly or explicitly while DL channel feedback is usuallyspecified by a feedback channel allocation IE, and the feedback channelallocation to a subscriber may be periodic.

In transmission of HARQ ACK/NACK for unpaired DL carriers, the DLcarrier information may be provided implicitly or explicitly in the HARQACK/NAK allocation either at the ACK/NACK channel level or at theACK/NACK region level. A separate HARQ ACK/NACK channel may be allocatedfor each DL carrier and an HARQ feedback for the unpaired DL carrier maybe sent via the corresponding HARQ channel. Alternatively, a separateHARQ region may be allocated for each DL carrier and HARQ feedback forthe unpaired DL carrier may be sent via a channel allocated in thecorresponding HARQ region.

The information about the UL carrier that carries the HARQ ACK/NACK foran unpaired DL carrier and the HARQ ACK/NACK region allocation may beeither pre-determined, (e.g., the primary UL carrier and a knownlocation), or signaled by DL PHY control signaling or MAC controlmessage.

Alternatively, multiple HARQ ACK/NACKs may be aggregated, (i.e., oneHARQ feedback is transmitted for multiple packets). With aggregatedACK/NACK, the HARQ feedback of two or more HARQ packets is logical ANDedtogether such that an ACK is generated if all packets have been decodedsuccessfully and a NACK is generated if at least one packet is notsuccessfully decoded. Upon receipt of an NACK, the base stationre-transmits all relevant packets. This scheme may save uplink resourcesat the cost of occasional redundant downlink retransmissions.

In accordance with another embodiment, the feedback information for theunpaired DL carrier (with or without feedback information for the pairedDL carrier(s)) may be reported via the MAC encoded feedback, (e.g., inMAC signal headers, subheaders, extended headers, or extendedsubheaders, or MAC management messages, etc.), on an activated ULcarrier. The activated UL carrier may be the primary UL carrier or anactivated secondary UL carrier. The MAC encoded feedback may contain thefeedback information for DL carriers, including activated paired orunpaired DL carriers. The DL carrier for specific feedback informationtransmitted in the MAC encoded header, subheader, extended header, ormessages may be identified by its DL carrier identifier provided in theMAC encoded feedback information or by a cyclic redundancy check (CRC)that is masked by the DL carrier identifier or its equivalent.

In order to minimize the MAC management or control overhead, the MACencoded feedback for supporting unpaired DL carriers may selectivelyinclude some of the feedback information. For example, the DL carrieridentifier may not be included in the MAC encoded feedback when thefeedback is for the default DL carrier, where the default DL carrier isthe corresponding DL carrier of the UL carrier where the feedback istransmitted. Another example is the MAC encoded feedback may not includethe feedback information for the paired DL carries under theconsideration that the fast feedback channels for the paired DL carriersprovide sufficient feedback information.

Embodiments for providing feedback for unpaired DL carrier through MACencoded feedback in IEEE 802.16m multicarrier operation are explainedhereafter. MAC management messages (report request and report responsemessages) may be defined for the base station to request a WTRU toprovide a DL channel feedback report and for the WTRU to report DLchannel feedback to the base station for multi-carrier operation. Thereport response from the WTRU may be sent either as a response to therequest from the base station or in an unsolicited manner. Table 2 showsthe 802.16 MAC management message format.

TABLE 2 Syntax Size (bit) Notes MAC Management Message( ) { Generic MAC16 Generic MAC header, including the Header (GMH) information fields ofthe Flow ID for MAC management flow and the length of the MAC managementmessage Type  8 MAC management message type. Contents variable MACmanagement message contents. }

In order to support the multicarrier operations with unpaired DL carrierconfigurations and allow a single report request and report responsemessage to request and report feedbacks for multiple DL carries for MACcontrol efficiency, the DL carrier information may be included in thereport request or report response messages. Table 3 and Table 4 showexamples of the report request and report response messages with DLcarrier information, respectively. In Tables 3 and 4, two 1-bitindicators are used to indicate the inclusions of the default DL carrierand/or non-default DL carrier. The default DL carrier is the DL carrierpaired with the UL carrier where the report response will betransmitted.

In the report request message in Table 3, the indicator“Default-DL-carrier-report-request-included” indicates whether thisreport request message includes the report request for the default DLcarrier, and the indicator“Non-default-DL-carrier-report-request-included” indicates whether thisreport request includes the report requests for the non-default DLcarrier. The report request includes the “DL carrier index” fieldindicating the DL carrier for the requested content.

TABLE 3 Syntax Size (bit) Notes MAC Management Message ( ) { Generic MACHeader 16  Generic MAC header, including the information fields of theFlow ID (GMH) for MAC management flow and the length of the MACmanagement message Type 8 MAC management message type for AAI_REP-REQDefault-DL-carrier-report- 1 Indicates if this AAI_REP-REQ includes thereport request for the request-included default DL carrier, where thedefault DL carrier is the DL carrier paired with the UL carrier wherethe corresponding AAI_REP-RSP will be transmitted; 0: not included 1:included Non-default-DL-carrier- 1 Indicated if this AAI_REP-report-request-included REQ includes the report requests for thenon-default DL carrier, 0: not included 1: included If(Default-DL-carrier- report-request-included) {  Report Request contentTBD Report request content for the default DL carrier } If(Non-default-DL-carrier- report-request-included) {  Number of DLCarriers (n N The number of DL carriers that this AAI_REP- ) REQ messagerequests the WTRU to report. For (i=0; i<n, i++) {   DL carrier index NThe DL carrier index of the DL carrier that the Report Request contentis about.   Report Request content TBD Report request content for thei-th DL carrier  } } }

In the report response message in Table 4, the indicators“Default-DL-carrier-report-included” and“Non-default-DL-carrier-report-included” indicate whether the report forthe default DL carrier and the report for the non-default DL carrier areincluded in this report response message, respectively. The reportresponse message may include the “DL carrier index” field indicating theDL carrier for the report content.

TABLE 4 Syntax Size (bit) Notes MAC Management Message( ) { Generic MACHeader (GMH) 16  Generic MAC header, including the information fields ofthe Flow ID for MAC management flow and the length of the MAC managementmessage Type 8 MAC management message type for AAI_REP-RSPDefault-DL-carrier-report-included 1 Indicates if this AAI_REP-RSPincludes the report for the default DL carrier, where the default DLcarrier is the DL carrier paired with the UL carrier where the AAI_REP-RSP is transmitted; 0: not included 1: includedNon-default-DL-carrier-report- 1 Indicated if this AAI_REP- included RSPincludes the report for the non-default DL carrier, 0: not included 1:included If (Default-DL-carrier-report- included) {  Report content TBDReport content for the default DL carrier } If(Non-default-DL-carrier-report- included) {  Number of reported DLCarriers (n) N The number of DL carriers that this AAI_REP- RSP messagecontains the WTRU’ reports.  For (i=0; i<n, i++) {   DL carrier index NThe DL carrier index of the DL carrier that the Report content is about.  Report content TBD Report content for the i-th DL carrier  } } }

The report request and report response messages may be used to reportthe non-default DL carrier(s), which would be useful when there is afast feedback channel allocated in the UL for the default DL carrier.Alternatively, the report request and report response messages may beused to report the default DL carrier, which would be useful when pairedDL carriers are required to have feedback information. When more thanone non-default DL carriers are included in the report response, a listof DL carrier identifiers and the corresponding report contents may beincluded in the report response message.

Alternatively, a MAC feedback signaling header may be used for reportrequest and report response for the channel feedback of the unpaired DLcarrier. Table 5 shows the basic format of the 802.16m MAC signalingheaders. No payload follows the MAC signaling header. The MAC signalingheader includes bits for the signaling header contents.

TABLE 5 Syntax Size (bit) Notes MAC Signaling Header( ) { FID 4 FlowIdentifier. Set to 0001 Type 4 MAC signaling header type. Length 3Indicates the length of the signaling header (includes the FID, Type,Length, reserved field and contents): 0b000 and 0b001: reserved 0b010: 2bytes 0b011: 3 bytes 0b100: 4 bytes 0b101: 5 bytes 0b110: 6 bytes 0b111:reserved Contents variable; MAC signaling header contents, with 36≦ thesize indicated by the length field. The size in bits is Length * 8 − 12}

Table 6 shows an example 802.16m MAC signaling header that may be usedby the WTRU to provide the base station with the feedback for the DLmulti-carriers (“Feedback-content” field in Table 6). A“DL-carrier-index” field is used to indicate the DL carrier associatedwith the feedback.

TABLE 6 Size Syntax (bit) Notes Feedback Signaling Header ( ) { FID  4Flow Identifier. This field indicates MAC signaling header. Type  4 MACsignaling header type for the Feedback signaling header STID 12 STID ofthe WTRU which sends the feedback. DL-carrier-index N DL carrier indexof the DL carrier which this feedback is about. Feedback-content 22 Thefeedback parameter values. }

The “station identity” (STID) field may not be needed when the MACsignaling header is transmitted in the UL allocation assignedspecifically to the WTRU, and the “DL carrier index” field may not beneeded when the feedback is for the paired DL carrier of the UL carrierwhere the feedback is transmitted. In such cases, the STID and the DLcarrier index may not be included in the MAC signaling header,respectively. In order to indicate the existence of the STID and the DLcarrier index, special flags (STID-inclusion-flag andDL-carrier-index-inclusion-flag) may be included in the MAC signalingheader, respectively. Table 7 shows an example MAC signaling header withthe STID-inclusion-flag and DL-carrier-index-inclusion-flag.

TABLE 7 Syntax Size(bit) Notes Feedback Signaling Header ( ) { FID 4Flow Identifier. This field indicates MAC signaling header. Type 4 MACsignaling header type for the Feedback signaling headerSTID-inclusion-flag 1 Indicate if the STID is included in this signalingheader 0: not included 1: included DL-carrier-Index-inclusion-flag 1Indicate if the DL carrier index is included in this signaling header:0: not included 1: included If STID-inclusion-flag { STID 12  STID ofthe WTRU which requests UL bandwidth. } If DL-carrier-index-inclusion-flag { DL-carrier-index N DL carrier index of the DL carrier which thisfeedback is about. } Feedback-content variable The feedback parametervalues. The size could be 20 bits, 26 bits, or 38 bits, depending on theSTD ID inclusion and/or DL carrier Index inclusion. Reserved TBDReserved. This field may be filled by 0 }

The DL CINR report may be piggybacked in the MAC Bandwidth Requestsignaling header without STID field. Table 8 shows an example of thepiggybacked CINR report in the Bandwidth Request signaling headerwithout STID. In Table 8, two fields, (“DL carrier index” and “CINR”),are added to the Bandwidth Request signaling header. The “DL carrierindex” field indicates the DL carrier for which the included CINR is,and the “CINR” field indicates the CINR measured by the WTRU.

TABLE 8 Syntax Size (bit) Notes BR without STID with CINR report header() { FID 4 Flow Identifier. This field indicates MAC signaling headerType 4 MAC signaling header type. BR Type 1 Indicates whether therequested bandwidth is incremental or aggregate. 0: incremental 1:aggregate BR Size 19  Bandwidth request size in bytes. BR FID 4 The FIDfor which UL bandwidth is requested. DL carrier index N DL carrier indexof the DL carrier whose CINR is reported below. CINR 7 indicates theCINR measured by the WTRU from the ABS. It may be interpreted as asingle value from −16.0 dB to 47.5 dB in units of 0.5 dB. Reserved 3Reserved. This field may be filled by 0 }

In 802.16m, the MAC encoded feedback may be included in a MAC extendedheader. Table 9 shows the basic format of 802.16m MAC extended header.

TABLE 9 Syntax Size (bit) Notes MAC extended header ( ) { LAST 1 LastExtended header indication: 0: one or more extended header follows thisextended header unless specified otherwise 1: this is the last extendedheader unless specified otherwise Type 8 MAC extended header type. BodyContents variable Extended header type dependent content. }

Table 10 shows an example of a MAC extended header that may be used bythe WTRU to provide feedback for the DL carriers. The MAC extendedheader includes “feedback-content” field for the feedback parametervalues, and “DL-carrier-index” field for indicating the DL carrierassociated with the feedback.

TABLE 10 Size Syntax (bit) Notes MAC extended header ( ) { LAST 1 LastExtended header indication: 0: one or more extended header follows thisextended header unless specified otherwise 1: this is the last extendedheader unless specified otherwise Type 8 MAC extended header type.DL-carrier-index N DL carrier index of the DL carrier which thisfeedback is about. Feedback-content The feedback parameter values. }

Although features and elements are described above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element can be used alone or in any combination with theother features and elements. In addition, the methods described hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable medium for execution by a computeror processor. Examples of computer-readable media include electronicsignals (transmitted over wired or wireless connections) andcomputer-readable storage media. Examples of computer-readable storagemedia include, but are not limited to, a read only memory (ROM), arandom access memory (RAM), a register, cache memory, semiconductormemory devices, magnetic media such as internal hard disks and removabledisks, magneto-optical media, and optical media such as CD-ROM disks,and digital versatile disks (DVDs). A processor in association withsoftware may be used to implement a radio frequency transceiver for usein a WTRU, UE, terminal, base station, RNC, or any host computer.

What is claimed:
 1. A method for use in a base station, the methodcomprising: allocating, by the base station, an uplink (UL) controlchannel associated with a single UL carrier, for a wirelesstransmit/receive unit (WTRU); transmitting, by the base station to theWTRU, a plurality of data signals via at least two downlink (DL)carriers using orthogonal frequency division multiple access (OFDMA) andmultiple input multiple output (MIMO); and receiving, by the basestation from the WTRU, hybrid automatic repeat request (HARQ)acknowledgment/negative-acknowledgement (ACK/NACK) information, for theplurality of data signals transmitted via the at least two DL carriers,on the UL control channel, wherein the HARQ ACK/NACK informationincludes at least two HARQ ACK/NACKs ANDed together.
 2. The method ofclaim 1 wherein the at least two of the HARQ ACK/NACKs are fromdifferent DL carriers.
 3. The method of claim 1 further comprisingtransmitting, by the base station to the WTRU, information including aset of the DL carriers for DL data transmission, wherein each of the DLcarriers of the set has an associated three bit indicator.
 4. The methodof claim 3 further comprising receiving, by the base station, feedbackinformation from the WTRU on the uplink control channel, wherein thefeedback information is derived using the three bit indicators for theDL carriers.
 5. The method of claim 1 wherein the base station is anLTE-Advanced base station.
 6. The method of claim 1 wherein the basestation is an 802.16m base station.
 7. The method of claim 1 furthercomprising: receiving, by the base station, on the UL control channelfrom the WTRU, a NACK for one of the plurality of data signalstransmitted via the at least two DL carriers; and retransmitting, by thebase station to the WTRU, the data signal via at least one DL carrier ofthe at least two DL carriers.
 8. The method of claim 1 wherein the HARQACK/NACK information includes at least two HARQ ACK/NACKs ANDed togetherfor each of the at least two DL carriers.
 9. A base station comprising:a processor configured to allocate an uplink (UL) control channelassociated with a single UL carrier, for a wireless transmit/receiveunit (WTRU); a transceiver operatively coupled to the processor, thetransceiver and the processor configured to transmit, to the WTRU, aplurality of data signals via at least two downlink (DL) carriers usingorthogonal frequency division multiple access (OFDMA) and multiple inputmultiple output (MIMO); and the transceiver configured to receive, fromthe WTRU, hybrid automatic repeat request (HARQ)acknowledgment/negative-acknowledgement (ACK/NACK) information, for theplurality of data signals transmitted via the at least two DL carriers,on the UL control channel, wherein the HARQ ACK/NACK informationincludes at least two HARQ ACK/NACKs ANDed together.
 10. The basestation of claim 9 wherein the at least two of the HARQ ACK/NACKs arefrom different DL carriers.
 11. The base station of claim 9 wherein theprocessor and the transceiver are further configured to transmit, to theWTRU, information including a set of the DL carriers for downlink datatransmission, wherein each of the DL carriers of the set has anassociated three bit indicator.
 12. The base station of claim 11 whereinthe transceiver is further configured to receive feedback informationfrom the WTRU on the uplink control channel, wherein the feedbackinformation is derived using the three bit indicators for the DLcarriers.
 13. The base station of claim 9 wherein the base station is anLTE-Advanced base station.
 14. The base station of claim 9 wherein thebase station is an 802.16m base station.
 15. The base station of claim 9wherein: the transceiver is further configured to receive, on the ULcontrol channel from the WTRU, a NACK for one of the plurality of datasignals transmitted via the at least two DL carriers; and the processorand the transceiver are further configured to retransmit, to the WTRU,the data signal via at least one DL carrier of the at least two DLcarriers.
 16. The base station of claim 9 wherein the HARQ ACK/NACKinformation includes at least two HARQ ACK/NACKs ANDed together for eachof the at least two DL carriers.
 17. A wireless transmit/receive unit(WTRU) comprising: a transceiver configured to receive an allocation ofan uplink (UL) control channel associated with a single UL carrier, fora wireless transmit/receive unit (WTRU); the transceiver configured toreceive a plurality of data signals via at least two downlink (DL)carriers using orthogonal frequency division multiple access (OFDMA) andmultiple input multiple output (MIMO); and a processor operativelycoupled to the transceiver, the processor and the transceiver configuredto transmit hybrid automatic repeat request (HARQ)acknowledgment/negative-acknowledgement (ACK/NACK) information, for theplurality of data signals received via the at least two DL carriers, onthe UL control channel, wherein the HARQ ACK/NACK information includesat least two HARQ ACK/NACKs ANDed together.
 18. The WTRU of claim 17wherein the at least two of the HARQ ACK/NACKs are from different DLcarriers.
 19. The WTRU of claim 17 wherein the processor and thetransceiver are further configured to receive information including aset of the DL carriers for downlink data transmission, wherein each ofthe DL carriers of the set has an associated three bit indicator. 20.The WTRU of claim 19 wherein the processor and the transceiver arefurther configured to transmit feedback information on the uplinkcontrol channel, wherein the feedback information is derived using thethree bit indicators for the DL carriers.
 21. The WTRU of claim 17wherein the WTRU is an LTE-Advanced WTRU.
 22. The WTRU of claim 17wherein the WTRU is an 802.16m base station.
 23. The WTRU of claim 17wherein: the processor and the transceiver are further configured totransmit on the UL control channel, a NACK for one of the plurality ofdata signals received via the at least two DL carriers; and the receiveris further configured to re-receive the data signal via at least one DLcarrier of the at least two DL carriers.
 24. The WTRU of claim 17wherein the HARQ ACK/NACK information includes at least two HARQACK/NACKs ANDed together for each of the at least two DL carriers.